Method and apparatus for locating and tracking documents and other objects

Abstract

An apparatus and method are described for a radio frequency document control system that enables the location of documents, such as office files, to be automatically and rapidly identified. A host transceiver, controlled via a PC, transmits a coded RF signal, at a first frequency, to individually addressable, low cost, local exciters/transceivers located on shelves and/or in drawers. The local exciters, which may be sequentially addressed, retransmit the coded RF signal at a second frequency via an antenna. A passive radio frequency identification tag, containing the same code as that transmitted by the local exciter and attached to a document, such as a file folder, when in the vicinity of the antenna of the local exciter, is energized by the RF field and modulates the second frequency signal from the local exciter. The second frequency signal modulated by the energized tag is then directly received by the host transceiver. A PC, coupled to the host transceiver, enables the system to automatically and rapidly identify, down to a specific shelf or drawer, the location of tagged documents in an office environment.

What is claimed is: 
     
       1. An apparatus for locating a particular object among one or more objects, comprising: a host transceiver;   a local exciter positioned in proximity to the one or more objects, wherein the local exciter receives a first signal transmitted by the host transceiver;   a tag affixed to each of the one or more objects, wherein the tag affixed to the particular object is excited by a second signal transmitted by the local exciter, wherein the excited tag selectively modulates the second signal from the local exciter, and the host transceiver directly receives the signal modulated by the excited tag; and   a computer coupled to the host transceiver, wherein the computer receives and sends data from and to the host transceiver.   
     
     
       2. The apparatus of claim 1, wherein the computer is coupled to the host transceiver through wire, radio frequency link, or optical link. 
     
     
       3. The apparatus of claim 1, wherein the second signal is of a second frequency, and the first signal is of a first frequency lower than the second frequency. 
     
     
       4. The apparatus of claim 1, wherein each tag has a unique identification code. 
     
     
       5. The apparatus of claim 1, wherein the host transceiver receives the modulated second signal at a distance of up to 50 feet. 
     
     
       6. The apparatus of claim 1, wherein the local exciter is coupled to one or more antennas. 
     
     
       7. The apparatus of claim 1, wherein the local exciter comprises a microcontroller, wherein the microcontroller switches the local exciter between a low power stand-by mode and a normal reception mode. 
     
     
       8. The apparatus of claim 7, wherein the microcontroller includes a non-volatile memory, and wherein the microcontroller periodically wakes up from the low power stand-by mode. 
     
     
       9. The apparatus of claim 1, wherein the host transceiver autocorrelates the modulated signal from the excited and selected tag, wherein the signal-to-noise ratio of the modulated signal from the tag is improved. 
     
     
       10. The apparatus of claim 1, further comprising an optical reader for reading optical information from the one or more objects, wherein data corresponding to an identification code on the tag affixed to the particular object is stored in a database accessed by the computer, and wherein data corresponding to optical information read from the particular object is stored in the database. 
     
     
       11. The apparatus of claim 1, wherein the host transceiver monitors the frequency of the second signal transmitted by the local exciter and adjusts a receiver frequency in the host transceiver to the frequency transmitted by the local exciter. 
     
     
       12. The apparatus of claim 1, wherein the tag includes a writeable memory. 
     
     
       13. The apparatus of claim 1, wherein the objects comprise documents. 
     
     
       14. The apparatus of claim 13, wherein the apparatus locates a particular document in an office or other document storage areas. 
     
     
       15. The apparatus of claim 1, wherein the objects comprise files, wherein the apparatus locates a particular file in an office or other document storage areas. 
     
     
       16. The apparatus of claim 1, wherein the computer is programmed so as to control the apparatus to perform a search cycle, wherein the particular object is located, wherein data representing the location of the particular object is stored by the computer. 
     
     
       17. The apparatus of claim 1, wherein the objects comprise files or documents. 
     
     
       18. The apparatus of claim 17, wherein the objects are stored in a container. 
     
     
       19. The apparatus of claim 18, wherein the container includes an aperture through which the second signal may pass. 
     
     
       20. The apparatus of claim 19, wherein the container comprises a filing cabinet. 
     
     
       21. The apparatus of claim 17, wherein tags are affixed in a peripheral portion of the files or documents. 
     
     
       22. The apparatus of claim 17, wherein tags are affixed on a tab protruding from the files or documents. 
     
     
       23. The apparatus of claim 17, wherein tags are affixed to a region of the file or document that is within a distance of one half of a wavelength of the second signal from an edge of the file or document, wherein the second signal is of a second frequency. 
     
     
       24. The apparatus of claim 1, wherein the host transceiver incorporates a diversity antenna to maximize the reception of the signal generated by the excited tag. 
     
     
       25. The apparatus of claim 1, wherein a frequency transmitted by the local exciter is adjusted over a range to achieve frequency diversity and to improve the reception of the signal generated by the excited tag. 
     
     
       26. The apparatus of claim 1, wherein a frequency transmitted by the local exciter is monotonically related to a power supply voltage to enable monitoring of the condition of a battery supply power to the local exciter. 
     
     
       27. An apparatus for locating a particular object among one or more objects, comprising: a host transceiver; a movable exciter, wherein the movable exciter receives a first signal from the a host transceiver;   a tag affixed to each of the one or more objects, wherein the tag affixed to the particular object is excited by a second signal transmitted by the movable exciter, wherein the excited tag selectively modulates the second signal from the movable exciter, and the host transceiver directly receives the signal modulated by the excited tag; and   a computer coupled to the host transceiver, wherein the computer receives and sends data from and to the host transceiver.   
     
     
       28. The apparatus of claim 27, wherein the computer is coupled to the host transceiver through wire, radio frequency link, or optical link. 
     
     
       29. The apparatus of claim 27, wherein the second signal is of a second frequency, and the first signal is of a first frequency lower than the second frequency. 
     
     
       30. The apparatus of claim 27, wherein each tag has a unique identification code. 
     
     
       31. The apparatus of claim 30, wherein the microcontroller includes a non-volatile memory, and wherein the microcontroller periodically wakes up from the low power stand-by mode. 
     
     
       32. The apparatus of claim 27, wherein the host transceiver receives the modulated second signal at a distance of up to 50 feet. 
     
     
       33. The apparatus of claim 27, wherein the movable exciter comprises a microcontroller, wherein the microcontroller switches the movable exciter between a low power stand-by mode and a normal reception mode. 
     
     
       34. The apparatus of claim 27, wherein the host transceiver autocorrelates the modulated signal from the excited tag, wherein the signal-to-noise ratio of the modulated signal from the tag is improved. 
     
     
       35. The apparatus of claim 27, further comprising an optical reader for reading optical information from the one or more objects, wherein data corresponding to an identification code on the tag affixed to the particular object is stored in a database accessed by the computer, and wherein data corresponding to optical information read from the particular object is stored in the database. 
     
     
       36. The apparatus of claim 27, wherein the host transceiver monitors the frequency of the second signal transmitted by the movable exciter and adjusts a receiver frequency in the host transceiver to the frequency transmitted by the movable exciter. 
     
     
       37. The apparatus of claim 27, wherein the tag includes a writeable memory. 
     
     
       38. The apparatus of claim 27, wherein the objects comprise documents. 
     
     
       39. The apparatus of claim 38, wherein the apparatus locates a particular document in an office or other document storage area. 
     
     
       40. The apparatus of claim 27, wherein the objects comprise files, wherein the apparatus locates a particular file in an office. 
     
     
       41. The apparatus of claim 27, wherein the computer is programmed so as to control the apparatus to perform a search cycle, wherein the particular object is located, wherein data representing the location of the particular object is stored by the computer. 
     
     
       42. The apparatus of claim 41, wherein the search cycle is initiated at the computer. 
     
     
       43. The apparatus of claim 41, wherein the search cycle is initiated at the movable exciter. 
     
     
       44. The apparatus of claim 27, wherein the objects comprise files or documents. 
     
     
       45. The apparatus of claim 44, wherein the objects are stored in a container. 
     
     
       46. The apparatus of claim 45, wherein the container includes a n aperture through which the second signal may pass. 
     
     
       47. The apparatus of claim 44, wherein the container comprises a filing cabinet. 
     
     
       48. The apparatus of claim 44, wherein tags are affixed in a peripheral portion of the files or documents. 
     
     
       49. The apparatus of claim 44, wherein tags are affixed on a tab protruding from the files or documents. 
     
     
       50. The apparatus of claim 44, where in tags are affixed to a region of the file or document that is within a distance of one half of a wavelength of the second signal from an edge of the file or document, wherein the second signal is of a second frequency. 
     
     
       51. The apparatus of claim 27, wherein the host transceiver incorporates a diversity antenna to maximize the reception of the signal generated by the excited tag. 
     
     
       52. The apparatus of claim 27, wherein a frequency transmitted by the local exciter is adjusted over a range to achieve frequency diversity and to improve the reception of the signal generated by the excited tag. 
     
     
       53. The apparatus of claim 27, wherein a frequency transmitted by the local exciter is monotonically related to a power supply voltage to enable monitoring of the condition of a battery supply power to the local exciter. 
     
     
       54. An apparatus for reading the identification code on an RFID tag attached to a particular object among one or more objects, comprising: a host transceiver;   an exciter, wherein the exciter receives a first signal from the host transceiver;   a tag affixed to each of the one or more objects, wherein the tag affixed to the particular object is excited by a second signal transmitted by the exciter, wherein the excited tag selectively modulates the second signal from the exciter, and the host transceiver receives the signal modulated by the excited tag, wherein the identification code is determined from the received modulated signal;   a computer coupled to the host transceiver, wherein the computer receives and sends data from and to the host transceiver.   
     
     
       55. The apparatus of claim 54, wherein the computer is coupled to the host transceiver through wire, radio frequency link, or optical link. 
     
     
       56. The apparatus of claim 54, wherein the second signal is of a second frequency, and the first signal is of a first frequency lower than the second frequency. 
     
     
       57. The apparatus of claim 54, wherein each tag has a unique identification code. 
     
     
       58. The apparatus of claim 54, further comprising an optical reader for reading optical information from the one or more objects, wherein data corresponding to an identification code on the tag affixed to the particular object is stored in a database accessed by a computer coupled to the host transceiver, and wherein data corresponding to optical information read from the particular object is stored in the database. 
     
     
       59. The apparatus of claim 54, wherein the host transceiver monitors the frequency of the second signal transmitted by the exciter and adjusts a receiver frequency in the host transceiver to the frequency transmitted by the exciter. 
     
     
       60. The apparatus of claim 54, wherein the tag includes a writeable memory. 
     
     
       61. The apparatus of claim 60, wherein the identification code is programmed into the writeable memory by the exciter. 
     
     
       62. The apparatus of claim 54, wherein the apparatus locates a particular document in an office. 
     
     
       63. The apparatus of claim 54, wherein the objects comprise files or documents. 
     
     
       64. The apparatus of claim 63, wherein the objects are stored in a container. 
     
     
       65. The apparatus of claim 64, wherein the container includes an aperture through which the second signal may pass. 
     
     
       66. The apparatus of claim 63, wherein tags are affixed in a peripheral portion of the files or documents. 
     
     
       67. The apparatus of claim 63, wherein tags are affixed on a tab protruding from the files or documents. 
     
     
       68. The apparatus of claim 63, wherein tags are affixed to a region of the file or document that is within a distance of one half of a wavelength of the second signal from an edge of the file or document, wherein the second signal is of a second frequency. 
     
     
       69. The apparatus of claim 54, wherein the host transceiver incorporates a diversity antenna to maximize the reception of the signal generated by the excited tag. 
     
     
       70. The apparatus of claim 54, wherein a frequency transmitted by the local exciter is adjusted over a range to achieve frequency diversity and to improve the reception of the signal generated by the excited tag. 
     
     
       71. The apparatus of claim 54, wherein a frequency transmitted by the local exciter is monotonically related to a power supply voltage to enable monitoring of the condition of a battery supply power to the local exciter. 
     
     
       72. An automatic system for locating a particular object among a plurality of objects, each of the objects having a tag affixed thereto, comprising: one or more host transceivers, wherein each host transceiver comprises a transmitter and a receiver;   one or more local exciters, wherein each local exciter comprises a receiver and a transmitter, and wherein the one or more local exciters receives a first signal from one of the one or more host transceivers, and, in response to the first signal, the one or more local exciters selectively transmit a second signal to tags affixed to one or more of the objects, wherein the tag affixed to the particular object is excited by the second signal, wherein the excited tag selectively modulates the second signal and one or more of the host transceivers directly receives the signal modulated by the excited tag; and   a computer coupled to the host transceiver, wherein the computer receives and sends data from and to the one or more host transceivers.   
     
     
       73. The apparatus of claim 72, wherein the computer is coupled to the host transceiver through wire, radio frequency link, or optical link. 
     
     
       74. The apparatus of claim 72, wherein the second signal is of a second frequency, and the first signal is of a first frequency lower than the second frequency. 
     
     
       75. The apparatus of claim 72, wherein each tag has a unique identification code. 
     
     
       76. The apparatus of claim 72, wherein the one or more host transceivers receive the modulated second signal at a distance of up to 50 feet. 
     
     
       77. The apparatus of claim 72, wherein the one or more local exciters are coupled to one or more antennas. 
     
     
       78. The apparatus of claim 72, wherein the one or more local exciters comprise a microcontroller, wherein the microcontroller switches the one or more local exciters between a low power stand-by mode and a normal reception mode. 
     
     
       79. The apparatus of claim 78, wherein the microcontroller includes a non-volatile memory, and wherein the microcontroller periodically wakes up from the low power stand-by mode. 
     
     
       80. The apparatus of claim 72, wherein the one or more host transceivers autocorrelates the modulated signal from the excited tag, wherein the signal-to-noise ratio of the modulated signal from the tag is improved. 
     
     
       81. The apparatus of claim 72, further comprising an optical reader for reading optical information from the one or more objects, wherein data corresponding to an identification code on the tag affixed to the particular object is stored in a database accessed by the computer, and wherein data corresponding to optical information read from the particular object is stored in the database. 
     
     
       82. The apparatus of claim 72, wherein the one or more host transceivers monitor the frequency of the second signal transmitted by the one or more local exciters and adjusts a receiver frequency in the one or more host transceivers to the frequency transmitted by the one or more local exciters. 
     
     
       83. The apparatus of claim 72, wherein the tag includes a writeable memory. 
     
     
       84. The apparatus of claim 72, wherein the objects comprise documents. 
     
     
       85. The apparatus of claim 84, wherein the apparatus locates a particular document in an office or other document storage area. 
     
     
       86. The apparatus of claim 72, wherein the objects comprise files, wherein the apparatus locates a particular file in an office or other document storage area. 
     
     
       87. The apparatus of claim 72, wherein the computer is programmed so as to control the apparatus to perform a search cycle, wherein the particular object is located, wherein data representing the location of the particular object is stored by the computer. 
     
     
       88. The apparatus of claim 72, wherein the objects comprise files or documents. 
     
     
       89. The apparatus of claim 88, wherein the objects are stored in a container. 
     
     
       90. The apparatus of claim 89, wherein the container includes an aperture through which the second signal may pass. 
     
     
       91. The apparatus of claim 88, wherein the container comprises a filing cabinet. 
     
     
       92. The apparatus of claim 88, wherein tags are affixed in a peripheral portion of the files or documents. 
     
     
       93. The apparatus of claim 88, wherein tags are affixed on a tab protruding from the files or documents. 
     
     
       94. The apparatus of claim 88, wherein tags are affixed to a region of the file or document that is within a distance of one half of a wavelength of the second signal from an edge of the file or document, wherein the second signal is of a second frequency. 
     
     
       95. The apparatus of claim 72, wherein a host transceiver sequentially addresses the one or more local exciters, wherein the host transceiver stops sequentially addressing the one or more local exciters if the particular object is located. 
     
     
       96. The apparatus of claim 72, wherein the host transceiver incorporates a diversity antenna to maximize the reception of the signal generated by the excited tag. 
     
     
       97. The apparatus of claim 72, wherein a frequency transmitted by the local exciter is adjusted over a range to achieve frequency diversity and to improve the reception of the signal generated by the excited tag. 
     
     
       98. The apparatus of claim 72, wherein a frequency transmitted by the local exciter is monotonically related to a power supply voltage to enable monitoring of the condition of a battery supply power to the local exciter. 
     
     
       99. An apparatus for locating a particular object among a plurality of objects, comprising: a host transceiver, wherein the host transceiver transmits a first signal;   a local exciter, wherein the local exciter receives the first signal from the host transceiver, and, in response, the local exciter transmits a second signal;   a plurality of tags, wherein a tag is attached to each of the plurality of objects, wherein the tag attached to the particular object is selectively excited by the second signal, and wherein the excited tag selectively modulates the second signal, wherein the selectively modulated second signal is received by the host transceiver and the location of the particular object is determined; and   a computer coupled to the host transceiver, wherein the computer receives and sends data from and to the one or more host transceivers.   
     
     
       100. The apparatus of claim 99, wherein the host transceiver incorporates a diversity antenna to maximize the reception of the signal generated by the excited tag. 
     
     
       101. The apparatus of claim 99, wherein a frequency transmitted by the local exciter is adjusted over a range to achieve frequency diversity and to improve the reception of the signal generated by the excited tag. 
     
     
       102. The apparatus of claim 99, wherein a frequency transmitted by the local exciter is monotonically related to a power supply voltage to enable monitoring of the condition of a battery supply power to the local exciter. 
     
     
       103. The apparatus of claim 99, wherein the host transceiver autocorrelates the modulated signal from the excited tag, wherein the signal to noise ratio of the modulated signal from the tag is improved. 
     
     
       104. The apparatus of claim 99, wherein the computer receives and transmits data from and to the host transceiver through wire, radio frequency link, or optical link. 
     
     
       105. The apparatus of claim 99, further comprising an exciter coupled to the host transceiver, wherein the exciter excites one or more of the tags, and wherein the apparatus reads identification data from one or more of the tags. 
     
     
       106. The apparatus of claim 99, further comprising an exciter coupled to the host transceiver, wherein the exciter programs data into one or more of the tags. 
     
     
       107. The apparatus of claim 99, wherein the objects comprise documents. 
     
     
       108. The apparatus of claim 107, wherein the apparatus locates a particular document in an office or other document storage area. 
     
     
       109. The apparatus of claim 99, wherein the objects comprise files, wherein the apparatus locates a particular file in an office or other document storage area. 
     
     
       110. The apparatus of claim 99, wherein the computer is programmed so as to control the apparatus to perform a search cycle, wherein the particular object is located, wherein data representing the location of the particular object is stored by the computer. 
     
     
       111. The apparatus of claim 99, wherein the objects comprise files or documents. 
     
     
       112. The apparatus of claim 111, wherein the objects are stored in a container. 
     
     
       113. The apparatus of claim 112, wherein the container includes an aperture through which the second signal may pass. 
     
     
       114. The apparatus of claim 112, wherein the container comprises a filing cabinet. 
     
     
       115. The apparatus of claim 111, wherein tags are affixed in a peripheral portion of the files or documents. 
     
     
       116. The apparatus of claim 111, wherein tags are affixed on a tab protruding from the files or documents. 
     
     
       117. The apparatus of claim 111, wherein tags are affixed to a region of the file or document that is within a distance of one half of a wavelength of the second signal from an edge of the file or document, wherein the second signal is of a second frequency. 
     
     
       118. An apparatus for locating a particular object comprising: one or more host transceivers, wherein each host transceiver comprises a transmitter and a receiver;   one or more movable exciters, wherein each exciter comprises a receiver and a transmitter, and wherein each exciter receives a first signal from the one or more host transmitters, and after receiving the first signal, the exciter transmits a second signal to a plurality of tags, wherein each tag is attached to an object, and wherein after the plurality of tags receive the second signal, the one or more host receivers receive a modulated second signal from the particular one of the plurality of tags, wherein the location of the particular object is determined; and   a computer coupled to the host transceiver, wherein the computer receives and sends data from and to the one or more host transceivers.   
     
     
       119. The apparatus of claim 118, wherein the host transceiver incorporates a diversity antenna to maximize the reception of the signal generated by the excited tag. 
     
     
       120. The apparatus of claim 118, wherein a frequency transmitted by the local exciter is adjusted over a range to achieve frequency diversity and to improve the reception of the signal generated by the excited tag. 
     
     
       121. The apparatus of claim 118, wherein the computer is coupled to the one or more host transceivers to receive and send data from and to the one or more host transceivers. 
     
     
       122. The apparatus of claim 118, wherein a user can manually scan a plurality of tagged objects using one of the one or more hand held exciters to locate the particular object. 
     
     
       123. The apparatus of claim 118, wherein the host transceiver autocorrelates the modulated signal from the excited tag, wherein the signal to noise ratio of the modulated signal from the tag is improved. 
     
     
       124. A method for locating a particular object among a plurality of objects, each of the objects having a tag affixed thereto, the method comprising the steps of: transmitting a first signal from one or more host transceivers to one or more local exciters;   transmitting a second signal from the one or more local exciters to the plurality of objects, wherein the second signal is received and modulated by the tag affixed to the particular object;   receiving the modulated second signal with one of the one or more host transceivers, wherein the location of the particular object is determined; and   coupling a computer to the one or more host transceivers, wherein the computer receives and sends data from and to the one or more host transceivers.   
     
     
       125. The method of 124, further comprising the step of communicating data indicative of the location of the particular object to a computer, wherein the computer displays the location and characteristics of the particular object. 
     
     
       126. The method of 125, further comprising the steps of: storing data indicative of characteristics of the objects into a database accessed by the computer; and   storing identification codes for each of the tags into a database accessed by the computer.   
     
     
       127. The method of claim 126, wherein at least a portion of the data indicative of characteristics of the objects are generated by optically scanning the objects. 
     
     
       128. The method of claim 126, further comprising the steps of: sequentially addressing the local exciters to determine the location of each of the objects;   storing data indicative of the location of each of the objects in the database accessed by the computer.   
     
     
       129. The method of claim 128, wherein an inventory of the objects is produced. 
     
     
       130. The method of claim 129, wherein at a first time a first inventory of the objects is produced, wherein at a second time a second inventory of the objects is produced. 
     
     
       131. The method of claim 130, further comprising the steps of: comparing the first inventory and the second inventory;   generating a list of objects in either the first inventory or the second inventory but not the second inventory or the first inventory.   
     
     
       132. The method of claim 126, wherein data indicative of user access to the database is stored in the database, wherein data indicative of user queries for particular objects are stored in the database, wherein data is retained in the database such that it may be determined which users queried for particular objects. 
     
     
       133. The method of claim 132, further comprising the steps of: sequentially addressing the local exciters to determine the location of each of the objects;   storing data indicative of the location of each of the objects in the database accessed by the computer.   
     
     
       134. The method of claim 133, wherein an inventory of the objects is produced. 
     
     
       135. The method of claim 134, wherein at a first time a first inventory of the objects is produced, wherein at a second time a second inventory of the objects is produced. 
     
     
       136. The method of claim 135, further comprising the steps of: comparing the first inventory and the second inventory;   generating a list of objects in either the first inventory or the second inventory but not the second inventory or the first inventory.   
     
     
       137. The method of claim 134, wherein a list of lost objects is produced based on the inventory and data in the database. 
     
     
       138. The method of claim 137, further comprising the step of comparing the list of lost objects with data indicative of user queries for particular objects. 
     
     
       139. The method of claim 138, further comprising the step of generating a list of user(s) who have queried for lost objects. 
     
     
       140. The method of claim 126, further comprising the steps of: sequentially addressing the local exciters to determine the location of a second particular one of the objects;   storing data indicative of the location of the second particular one of the objects if a modulated second signal from the second particular one of the objects is received by the host transceiver; and   indicating a lost-object condition if all of the local exciters are sequentially addressed and the modulated second signal from the second particular one of the objects is not received by the host transceiver.   
     
     
       141. The method of claim 126, wherein the computer is programmed so as to control the apparatus to perform a search cycle, wherein the particular object is located, wherein data representing the location of the particular object is stored by the computer. 
     
     
       142. The method of claim 124, wherein an exciter is coupled to the host transceiver, wherein the exciter excites one or more of the tags and reads identification data from one or more of the tags. 
     
     
       143. The method of claim 124, wherein an exciter coupled to the host transceiver, wherein the exciter programs data into one or more of the tags. 
     
     
       144. The method of claim 124, wherein the objects comprise documents. 
     
     
       145. The method of claim 144, wherein the method locates a particular document in an office or other document storage area. 
     
     
       146. The method of claim 124, wherein the objects comprise files, wherein the method locates a particular file in an office. 
     
     
       147. The method of claim 146, wherein the office includes at least one area in which the objects are stored, wherein the one area has an entry through a user must pass to enter into or exit from the one area, wherein one or more independent, stand alone, or readers are coupled to the computer and are positioned in proximity to the entry, wherein a reader interrogates one or more of the tags and reads identification data from one or more of the tags as a user passes through the entry. 
     
     
       148. The method of claim 147, wherein the reader also interrogates a tag that identifies the user passing through the entry. 
     
     
       149. The method of claim 148, wherein a computer coupled to an independent reader or readers records which users passed through the entry and which objects passed through the entry with each user. 
     
     
       150. The method of claim 149, wherein the computer accesses a database storing data indicative of the objects, wherein the database stores data indicative of the objects and which users removed or returned the objects from or to the area. 
     
     
       151. The method of claim 124, wherein the objects comprise files or documents. 
     
     
       152. The method of claim 124, wherein the objects are stored in a container. 
     
     
       153. The method of claim 152, wherein the container includes an aperture through which the second signal may pass. 
     
     
       154. The method of claim 153, wherein the container comprises a filing cabinet. 
     
     
       155. The method of claim 152, wherein tags are affixed in a peripheral portion of the files or documents. 
     
     
       156. The method of claim 152, wherein tags are affixed on a tab protruding from the files or documents. 
     
     
       157. The method of claim 152, wherein tags are affixed to a region of the file or document that is within a distance of one half of a wavelength of the second signal from an edge of the file or document, wherein the second signal is of a second frequency. 
     
     
       158. The method of claim 124, wherein the host transceiver incorporates a diversity antenna to maximize the reception of the signal generated by the excited tag. 
     
     
       159. The method of claim 124, wherein a frequency transmitted by the local exciter is adjusted over a range to achieve frequency diversity and to improve the reception of the signal generated by the excited tag. 
     
     
       160. The method of claim 124, wherein a frequency transmitted by the local exciter is monotonically related to a power supply voltage to enable monitoring of the condition of a battery supply power to the local exciter. 
     
     
       161. The method of claim 124, wherein the host transceiver autocorrelates the modulated signal from the excited tag, wherein the signal to noise ratio of the modulated signal from the tag is improved. 
     
     
       162. A business environment in which a particular object may be located, comprising: at least one area having a plurality of containers for storing a plurality of objects;   one or more host transceivers, wherein each host transceiver comprises a transmitter and a receiver;   one or more local exciters, wherein each local exciter comprises a receiver and a transmitter and at least one local exciter is positioned within each of the containers, and wherein the one or more local exciters receives a first signal from one of the one or more host transceivers, and, in response to the first signal, the one or more local exciters selectively transmit a second signal to tags affixed to one or more of the objects, wherein the tag affixed to the particular object is excited by the second signal, wherein the excited tag selectively modulates the second signal and one or more of the host transceivers directly receives the signal modulated by the excited tag; and   a computer coupled to the host transceiver, wherein the computer receives and sends data from and to the one or more host transceivers, wherein the computer displays information indicative of the container containing the particular object.   
     
     
       163. The environment of claim 162, wherein the one or more local exciters are coupled to one or more antennas positioned within the containers. 
     
     
       164. The environment of claim 162, wherein the one or more local exciters comprise a microcontroller, wherein the microcontroller switches the one or more local exciters between a low power stand-by mode and a normal reception mode. 
     
     
       165. The environment of claim 164, wherein the microcontroller includes a non-volatile memory, and wherein the microcontroller periodically wakes up from the low power stand-by mode. 
     
     
       166. The environment of claim 162, further comprising an optical reader for reading optical information from the one or more objects, wherein data corresponding to an identification code on the tag affixed to the particular object is stored in a database accessed by the computer, and wherein data corresponding to optical information read from the particular object is stored in the database. 
     
     
       167. The environment of claim 162, wherein the objects comprise documents. 
     
     
       168. The environment of claim 167, wherein a particular document is located in an office. 
     
     
       169. The environment of claim 162, wherein the objects comprise files, wherein a particular file is located in an office. 
     
     
       170. The environment of claim 162, wherein the computer is programmed so as to control the apparatus to perform a search cycle, wherein the particular object is located, wherein data representing the location of the particular object is stored by the computer. 
     
     
       171. The environment of claim 162, wherein the containers include an aperture through which the second signal may pass. 
     
     
       172. The environment of claim 162, wherein the containers comprise filing cabinets. 
     
     
       173. The environment of claim 172, wherein at least some of the filing cabinets are positioned around a centrally located host transceiver. 
     
     
       174. The environment of claim 162, wherein the host transceiver incorporates a diversity antenna to maximize the reception of the signal generated by the excited tag. 
     
     
       175. The environment of claim 162, wherein a frequency transmitted by the local exciter is adjusted over a range to achieve frequency diversity and to improve the reception of the signal generated by the excited tag. 
     
     
       176. The environment of claim 162, wherein a frequency transmitted by the local exciter is monotonically related to a power supply voltage to enable monitoring of the condition of a battery supply power to the local exciter. 
     
     
       177. The environment of claim 162, wherein the host transceiver autocorrelates the modulated signal from the excited tag, wherein the signal to noise ratio of the modulated signal from the tag is improved.